Biology subjects

Sosnowski, P.

Publications and source records attributed to Sosnowski, P..

3 recordsLinked to original sources

bioRxiv2024

Development of a small-molecule epigenetic regenerative therapy. Subcutaneous administration of alginate formulations with high loads of zebularine and retinoic acid promotes tissue growth, vascularization and innervation and induces extensive epigenetic repatterning

Recently, zebularine, a small-molecule epigenetic inhibitor and retinoic acid, acting as a transcriptional activator, have been found to induce tissue regeneration. In this study, the pro-regenerative properties of zebularine and retinoic acid were combined with the potential of the alginate carrier to expand its therapeutic possibilities. Alginate formulations of zebularine and retinoic acid were developed for subcutaneous administration to mice. Hydrophilic zebularine formed a homogenous formulation with extreme drug loadings reaching 240 mg of zebularine per 1 ml of 2% sodium alginate, while hydrophobic retinoic acid, 0.8 mg/ml, dispersed as fine crystals. Cell culture tests exhibited no significant cytotoxicity of the alginate formulations. Subcutaneous administration of zebularine and retinoic acid in 2% sodium alginate promoted regenerative responses in a mouse model of ear pinna punch wound mice involving the restoration of tissue architecture, nerve and vessel growth, and extensive epigenetic and transcriptional repatterning with no adverse effects observed in the animals. Significant trancriptomic responses to the epigenetic treatment included the induction of epithelium development genes contrasted with the downregulation of muscle development genes on day 7 post-injury. Among the remarkable changes in global gene methylation are those in neurodevelopmental genes. In vitro studies showed rapid zebularine but no retinoic acid discharge from the alginate formulations. Live ultrasound imaging demonstrated gradual absorption of the subcutaneously injected alginate formulations, which may explain the in vivo activity of retinoic acid following subcutaneous administration. Effective induction of tissue regeneration together with a high safety profile and of the subcutaneously administered pro-regenerative alginate formulations opens the way to testing further regenerative therapies for hard-to-reach lesions.

bioengineering↗

bioRxiv2020

The viral protein NSP1 acts as a ribosome gatekeeper for shutting down host translation and fostering SARS-CoV-2 translation

SARS-CoV-2 coronavirus is responsible for Covid-19 pandemic. In the early phase of infection, the single-strand positive RNA genome is translated into non-structural proteins (NSP). One of the first proteins produced during viral infection, NSP1, binds to the host ribosome and blocks the mRNA entry channel. This triggers translation inhibition of cellular translation. In spite of the presence of NSP1 on the ribosome, viral translation proceeds however. The molecular mechanism of the so-called viral evasion to NSP1 inhibition remains elusive. Here, we confirm that viral translation is maintained in the presence of NSP1. The evasion to NSP1-inhibition is mediated by the cis-acting RNA hairpin SL1 in the 5UTR of SARS-CoV-2. NSP1-evasion can be transferred on a reporter transcript by SL1 transplantation. The apical part of SL1 is only required for viral translation. We show that NSP1 remains bound on the ribosome during viral translation. We suggest that the interaction between NSP1 and SL1 frees the mRNA accommodation channel while maintaining NSP1 bound to the ribosome. Thus, NSP1 acts as a ribosome gatekeeper, shutting down host translation or fostering SARS-CoV-2 translation depending on the presence of the SL1 5UTR hairpin. SL1 is also present and necessary for translation of sub-genomic RNAs in the late phase of the infectious program. Consequently, therapeutic strategies targeting SL1 should affect viral translation at early and late stages of infection. Therefore, SL1 might be seen as a genuine Achille heel of the virus.

molecular biology↗

bioRxiv2018

The CryoEM Structure of the Ribosome Maturation Factor Rea1

The biogenesis of the 60S ribosomal subunit is initiated in the nucleus where rRNAs and proteins form pre-60S particles. These pre-60S particles mature by transiently interacting with various assembly factors. The ~5000 amino-acid AAA+ ATPase Rea1 (or Midasin) generates force to mechanically remove assembly factors from pre-60S particles, which promotes their export to the cytosol. Here we present three Rea1 cryoEM structures. We visualize the Rea1 engine, a hexameric ring of AAA+ domains, and identify an -helical bundle of AAA2 as a major ATPase activity regulator. The -helical bundle interferes with nucleotide induced conformational changes that create a docking site for the substrate binding MIDAS domain of Rea1 on the AAA+ ring. Furthermore, we reveal the architecture of the Rea1 linker, which is involved in force generation and extends from the AAA+ ring. The data presented here provide insights into the mechanism of one of the most complex ribosome maturation factors.

molecular biology↗